Sunday, February 18, 2018

Observing Leaves

Flowers are showy and essential for reproduction by their plants, but leaves contain the photosynthetic aparatus and are the source of food that plants self-generate. Leaves are essential to the world's economy, providing the basic materials that feed both plants and animals. Of course there are other synthetic pathways and some stems are photosynthetic, but far and away most of the energy from the sun is captured by leaves and turned into plant biomass, which is subsequently eaten by just about everything.

Leaves have work they must do and that creates design constraints on them. Yet look at this diversity:

I can go on and on. This is only a small bit of the diversity of leaf shapes and sizes. Look around and notice the variation. Trying to make order, people have observed that closely related plants will often have similar leaves, grasses for example. Another source of similarity is a stressful habitat; for example many desert plants have small, tough leaves. Conversely, humans have selected for different colors of leaves for ornamental plants and are attracted to unusual leaf shapes. So there's lots to notice.